[PATCH net-next v2 0/4] net: ethernet: Convert to platform remove callback returning void

[PATCH net-next v2 0/4] net: ethernet: Convert to platform remove callback returning void

[Uwe Kleine-König]

Hello,

in (implicit) v1 of this series
(https://lore.kernel.org/netdev/20231117091655.872426-1-u.kleine-koenig@pengutronix.de)
I tried to address the resource leaks in the three cpsw drivers. However
this is hard to get right without being able to test the changes. So
here comes a series that just converts all drivers below
drivers/net/ethernet to use .remove_new() and adds a comment about the
potential leaks for someone else to fix the problem.

See commit 5c5a7680e67b ("platform: Provide a remove callback that
returns no value") for an extended explanation and the eventual goal.
The TL;DR; is to prevent bugs like the three noticed here.

Note this series results in no change of behaviour apart from improving
the error message for the three cpsw drivers from

	remove callback returned a non-zero value. This will be ignored.

to

	Failed to resume device (-ESOMETHING)

. 

Best regards
Uwe

Uwe Kleine-König (4):
  net: ethernet: ti: am65-cpsw: Convert to platform remove callback returning void
  net: ethernet: ti: cpsw: Convert to platform remove callback returning void
  net: ethernet: ti: cpsw-new: Convert to platform remove callback returning void
  net: ethernet: ezchip: Convert to platform remove callback returning void

 drivers/net/ethernet/ezchip/nps_enet.c   |  6 ++----
 drivers/net/ethernet/ti/am65-cpsw-nuss.c | 15 ++++++++++-----
 drivers/net/ethernet/ti/cpsw.c           | 15 ++++++++++-----
 drivers/net/ethernet/ti/cpsw_new.c       | 15 ++++++++++-----
 4 files changed, 32 insertions(+), 19 deletions(-)

base-commit: 8c87404c76c1911a7ec5b61bf3b2c3858cb95de1
-- 
2.42.0

[PATCH net-next v2 1/4] net: ethernet: ti: am65-cpsw: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Replace the error path returning a non-zero value by an error message
and a comment that there is more to do. With that this patch results in
no change of behaviour in this driver apart from improving the error
message.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/net/ethernet/ti/am65-cpsw-nuss.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index 7992a76ed4d8..7651f90f51f2 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -3028,7 +3028,7 @@ static int am65_cpsw_nuss_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int am65_cpsw_nuss_remove(struct platform_device *pdev)
+static void am65_cpsw_nuss_remove(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct am65_cpsw_common *common;
@@ -3037,8 +3037,14 @@ static int am65_cpsw_nuss_remove(struct platform_device *pdev)
 	common = dev_get_drvdata(dev);
 
 	ret = pm_runtime_resume_and_get(&pdev->dev);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		/* Note, if this error path is taken, we're leaking some
+		 * resources.
+		 */
+		dev_err(&pdev->dev, "Failed to resume device (%pe)\n",
+			ERR_PTR(ret));
+		return;
+	}
 
 	am65_cpsw_unregister_devlink(common);
 	am65_cpsw_unregister_notifiers(common);
@@ -3056,7 +3062,6 @@ static int am65_cpsw_nuss_remove(struct platform_device *pdev)
 
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
-	return 0;
 }
 
 static int am65_cpsw_nuss_suspend(struct device *dev)
@@ -3156,7 +3161,7 @@ static struct platform_driver am65_cpsw_nuss_driver = {
 		.pm = &am65_cpsw_nuss_dev_pm_ops,
 	},
 	.probe = am65_cpsw_nuss_probe,
-	.remove = am65_cpsw_nuss_remove,
+	.remove_new = am65_cpsw_nuss_remove,
 };
 
 module_platform_driver(am65_cpsw_nuss_driver);
-- 
2.42.0

Re: [PATCH net-next v2 1/4] net: ethernet: ti: am65-cpsw: Convert to platform remove callback returning void

[Roger Quadros]

On 28/11/2023 19:38, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> 
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new(), which already returns void. Eventually after all drivers
> are converted, .remove_new() will be renamed to .remove().
> 
> Replace the error path returning a non-zero value by an error message
> and a comment that there is more to do. With that this patch results in
> no change of behaviour in this driver apart from improving the error
> message.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Roger Quadros <rogerq@kernel.org>

[PATCH net-next v2 2/4] net: ethernet: ti: cpsw: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Replace the error path returning a non-zero value by an error message
and a comment that there is more to do. With that this patch results in
no change of behaviour in this driver apart from improving the error
message.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/net/ethernet/ti/cpsw.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index ca4d4548f85e..ea85c6dd5484 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -1722,14 +1722,20 @@ static int cpsw_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int cpsw_remove(struct platform_device *pdev)
+static void cpsw_remove(struct platform_device *pdev)
 {
 	struct cpsw_common *cpsw = platform_get_drvdata(pdev);
 	int i, ret;
 
 	ret = pm_runtime_resume_and_get(&pdev->dev);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		/* Note, if this error path is taken, we're leaking some
+		 * resources.
+		 */
+		dev_err(&pdev->dev, "Failed to resume device (%pe)\n",
+			ERR_PTR(ret));
+		return;
+	}
 
 	for (i = 0; i < cpsw->data.slaves; i++)
 		if (cpsw->slaves[i].ndev)
@@ -1740,7 +1746,6 @@ static int cpsw_remove(struct platform_device *pdev)
 	cpsw_remove_dt(pdev);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
-	return 0;
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -1795,7 +1800,7 @@ static struct platform_driver cpsw_driver = {
 		.of_match_table = cpsw_of_mtable,
 	},
 	.probe = cpsw_probe,
-	.remove = cpsw_remove,
+	.remove_new = cpsw_remove,
 };
 
 module_platform_driver(cpsw_driver);
-- 
2.42.0

Re: [PATCH net-next v2 2/4] net: ethernet: ti: cpsw: Convert to platform remove callback returning void

[Roger Quadros]

On 28/11/2023 19:38, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> 
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new(), which already returns void. Eventually after all drivers
> are converted, .remove_new() will be renamed to .remove().
> 
> Replace the error path returning a non-zero value by an error message
> and a comment that there is more to do. With that this patch results in
> no change of behaviour in this driver apart from improving the error
> message.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Roger Quadros <rogerq@kernel.org>

[PATCH net-next v2 3/4] net: ethernet: ti: cpsw-new: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Replace the error path returning a non-zero value by an error message
and a comment that there is more to do. With that this patch results in
no change of behaviour in this driver apart from improving the error
message.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/net/ethernet/ti/cpsw_new.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
index 0e4f526b1753..498c50c6d1a7 100644
--- a/drivers/net/ethernet/ti/cpsw_new.c
+++ b/drivers/net/ethernet/ti/cpsw_new.c
@@ -2037,14 +2037,20 @@ static int cpsw_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int cpsw_remove(struct platform_device *pdev)
+static void cpsw_remove(struct platform_device *pdev)
 {
 	struct cpsw_common *cpsw = platform_get_drvdata(pdev);
 	int ret;
 
 	ret = pm_runtime_resume_and_get(&pdev->dev);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		/* Note, if this error path is taken, we're leaking some
+		 * resources.
+		 */
+		dev_err(&pdev->dev, "Failed to resume device (%pe)\n",
+			ERR_PTR(ret));
+		return;
+	}
 
 	cpsw_unregister_notifiers(cpsw);
 	cpsw_unregister_devlink(cpsw);
@@ -2055,7 +2061,6 @@ static int cpsw_remove(struct platform_device *pdev)
 	cpsw_remove_dt(cpsw);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
-	return 0;
 }
 
 static int __maybe_unused cpsw_suspend(struct device *dev)
@@ -2116,7 +2121,7 @@ static struct platform_driver cpsw_driver = {
 		.of_match_table = cpsw_of_mtable,
 	},
 	.probe = cpsw_probe,
-	.remove = cpsw_remove,
+	.remove_new = cpsw_remove,
 };
 
 module_platform_driver(cpsw_driver);
-- 
2.42.0

Re: [PATCH net-next v2 3/4] net: ethernet: ti: cpsw-new: Convert to platform remove callback returning void

[Roger Quadros]

On 28/11/2023 19:38, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> 
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new(), which already returns void. Eventually after all drivers
> are converted, .remove_new() will be renamed to .remove().
> 
> Replace the error path returning a non-zero value by an error message
> and a comment that there is more to do. With that this patch results in
> no change of behaviour in this driver apart from improving the error
> message.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Roger Quadros <rogerq@kernel.org>

[PATCH net-next v2 4/4] net: ethernet: ezchip: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/net/ethernet/ezchip/nps_enet.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ezchip/nps_enet.c b/drivers/net/ethernet/ezchip/nps_enet.c
index 4d7184d46824..07c2b701b5fa 100644
--- a/drivers/net/ethernet/ezchip/nps_enet.c
+++ b/drivers/net/ethernet/ezchip/nps_enet.c
@@ -633,7 +633,7 @@ static s32 nps_enet_probe(struct platform_device *pdev)
 	return err;
 }
 
-static s32 nps_enet_remove(struct platform_device *pdev)
+static void nps_enet_remove(struct platform_device *pdev)
 {
 	struct net_device *ndev = platform_get_drvdata(pdev);
 	struct nps_enet_priv *priv = netdev_priv(ndev);
@@ -641,8 +641,6 @@ static s32 nps_enet_remove(struct platform_device *pdev)
 	unregister_netdev(ndev);
 	netif_napi_del(&priv->napi);
 	free_netdev(ndev);
-
-	return 0;
 }
 
 static const struct of_device_id nps_enet_dt_ids[] = {
@@ -653,7 +651,7 @@ MODULE_DEVICE_TABLE(of, nps_enet_dt_ids);
 
 static struct platform_driver nps_enet_driver = {
 	.probe = nps_enet_probe,
-	.remove = nps_enet_remove,
+	.remove_new = nps_enet_remove,
 	.driver = {
 		.name = DRV_NAME,
 		.of_match_table  = nps_enet_dt_ids,
-- 
2.42.0

Re: [PATCH net-next v2 0/4] net: ethernet: Convert to platform remove callback returning void

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Tue, 28 Nov 2023 18:38:24 +0100 you wrote:
> Hello,
> 
> in (implicit) v1 of this series
> (https://lore.kernel.org/netdev/20231117091655.872426-1-u.kleine-koenig@pengutronix.de)
> I tried to address the resource leaks in the three cpsw drivers. However
> this is hard to get right without being able to test the changes. So
> here comes a series that just converts all drivers below
> drivers/net/ethernet to use .remove_new() and adds a comment about the
> potential leaks for someone else to fix the problem.
> 
> [...]

Here is the summary with links:
  - [net-next,v2,1/4] net: ethernet: ti: am65-cpsw: Convert to platform remove callback returning void
    https://git.kernel.org/netdev/net-next/c/7234dc5ccba6
  - [net-next,v2,2/4] net: ethernet: ti: cpsw: Convert to platform remove callback returning void
    https://git.kernel.org/netdev/net-next/c/7ac3f867a358
  - [net-next,v2,3/4] net: ethernet: ti: cpsw-new: Convert to platform remove callback returning void
    https://git.kernel.org/netdev/net-next/c/a76772e2fd83
  - [net-next,v2,4/4] net: ethernet: ezchip: Convert to platform remove callback returning void
    https://git.kernel.org/netdev/net-next/c/7ec1bb2ce64b

You are awesome, thank you!
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